Coerce string integer destinations to file descriptors

docs/transports.md

@@ -220,7 +220,7 @@ const transport = pino.transport({
 pino(transport)
 ```
 
-The `options.destination` property may also be a number to represent a file descriptor. Typically this would be `1` to write to STDOUT or `2` to write to STDERR. If `options.destination` is not set, it defaults to `1` which means logs will be written to STDOUT.
+The `options.destination` property may also be a number to represent a filedescriptor. Typically this would be `1` to write to STDOUT or `2` to write to STDERR. If `options.destination` is not set, it defaults to `1` which means logs will be written to STDOUT. If `options.destination` is a string integer, e.g. `'1'`, it will be coerced to a number and used as a file descriptor. If this is not desired, provide a full path, e.g. `/tmp/1`.
 
 The difference between using the `pino/file` transport builtin and using `pino.destination` is that `pino.destination` runs in the main thread, whereas `pino/file` sets up `pino.destination` in a worker thread.
 

file.js

@@ -4,7 +4,15 @@ const pino = require('./pino')
 const { once } = require('events')
 
 module.exports = async function (opts = {}) {
-  const destination = pino.destination({ dest: opts.destination || 1, sync: false })
+  const destination = pino.destination({ dest: normalizeDest(opts.destination || 1), sync: false })
   await once(destination, 'ready')
   return destination
 }
+
+function normalizeDest (destination) {
+  const fd = Number(destination)
+  if (typeof destination === 'string' && Number.isFinite(fd)) {
+    return fd
+  }
+  return destination
+}

test/fixtures/transport-string-stdout.js

@@ -0,0 +1,9 @@
+'use strict'
+
+const pino = require('../..')
+const transport = pino.transport({
+  target: 'pino/file',
+  options: { destination: '1' }
+})
+const logger = pino(transport)
+logger.info('Hello')

test/transport/core.test.js

@@ -305,6 +305,18 @@ test('stdout in worker', async ({ not }) => {
   not(strip(actual).match(/Hello/), null)
 })
 
+test('string integer destination', async ({ not }) => {
+  let actual = ''
+  const child = execa(process.argv[0], [join(__dirname, '..', 'fixtures', 'transport-string-stdout.js')])
+
+  child.stdout.pipe(writer((s, enc, cb) => {
+    actual += s
+    cb()
+  }))
+  await once(child, 'close')
+  not(strip(actual).match(/Hello/), null)
+})
+
 test('pino transport options with target', async ({ teardown, same }) => {
   const destination = join(
     os.tmpdir(),